Batch-Cook Mackerel, Potato & Pea Traybake Fingers

Ingredients

• 300 g (10½ oz) Atlantic mackerel fillets, skinned and pin-boned
• 400 g (14 oz) floury potatoes, peeled and cut into 3 cm chunks
• 120 g (1 cup) frozen peas
• 1 medium egg, beaten
• 2 tbsp (14 g) ground flaxseed (linseed)
• 1 tbsp (15 ml) olive or rapeseed oil, plus a little for the tin
• 1 tbsp chopped fresh dill or parsley
• Finely grated zest of ½ unwaxed lemon

Method

1. 1. Heat the oven to 200°C / 180°C fan / 400°F and line a 20 x 20 cm tin with baking parchment.
2. 2. Boil the potatoes in unsalted water for about 15 minutes; add the peas for the final 3 minutes, then drain well.
3. 3. While the potatoes cook, sit the mackerel fillets in a steamer basket over the pan and steam for 6–8 minutes, until opaque, flaking and 63°C at the centre.
4. 4. Mash the potatoes and peas together, deliberately crushing every pea against the side of the pan so that none stay whole and round, then flake in the mackerel, running every flake between your fingers to check for bones.
5. 5. Fold in the beaten egg, ground flaxseed, oil, herbs and lemon zest until the mixture just holds together.
6. 6. Press evenly into the lined tin, about 2 cm deep, and bake for 20–25 minutes until set right through and lightly golden — the egg must be fully cooked, with no soft or wet mixture in the centre.
7. 7. Cool completely in the tin and lift out on the parchment. Cut the slab in half down the middle, then cut each half crosswise into 6, giving 12 fingers about 10 cm long and 3 cm wide.
8. 8. To batch-freeze: open-freeze the fingers on a tray, then bag them for up to 1 month. Reheat from frozen at 180°C for 15 minutes until piping hot all the way through, then cool to lukewarm before serving — reheat once only.